1. Field of the Invention
The present invention is related to a method for controlling the rotation speed of a compressor, and particularly to a method for controlling the rotation speed of a compressor for a refrigerator based on the number and accumulated time interval of door openings.
2. Description of the Art
As is well known, a refrigerator is an appliance which preserves food at low temperature by cooling a definite space by the evaporation heat of a liquified gas. To effectively execute the afore-mentioned action, the refrigerator includes a refrigerating cycle which repeats four actions of compression, condensation, expansion, evaporation. An enclosed compressor is used in executing the compression action. The enclosed compressor is formed of an electric motor and a piston (in case of a reciprocating compressor) respectively arranged in an air-tight housing.
In the afore-mentioned configuration, as the axis of the motor is rotated, the piston connected thereto reciprocally moves within the air-tight housing, thereby inhaling and then compressing refrigerant. The compressed refrigerant is then discharged from the air-tight housing to execute the next action, that is, condensation action.
FIG. 1 is a block diagram of a conventional control apparatus for a refrigerator. Referring to FIG. 1, a conventional control apparatus for a refrigerator may include a temperature sensing section 20 for sensing the temperature of a freezing compartment, a door sensing section 30 for sensing the opening and closing state of the freezing compartment door, a compressor driving section 40 for driving the compressor, a fan driving section 50 for driving a fan which circulates cold air generated from an evaporator (not shown) in the freezing and refrigerating compartments, and a control section 10 for controlling the whole operation of the refrigerator.
In the control apparatus having the afore-mentioned configuration, when the temperature of the freezing compartment sensed by temperature sensing section 20 is higher than a set value, the control section 10, normally embodied by a microprocessor, outputs a control signal to the compressor driving section 40 so that the compressor may be activated. However, when the temperature of the freezing compartment is lower than the set value by the activation of the compressor, the control section 10 outputs control signals to the compressor driving section 40 and fan driving section 50 so that the activation of the compressor and fan may be stopped. Here, the fan is controlled to be stopped the moment the freezing compartment door is opened, whereas the compressor is controlled according to the temperature of the freezing compartment regardless of the opening and closing state of the freezing compartment door.
However, the conventional control apparatus for a refrigerator has a problem in that it cannot rapidly lower the temperature of the freezing compartment although the user lowers the set temperature of the freezing compartment in order to cancel the increase in the temperature of the freezing compartment caused by the frequent use of the refrigerator. For example, although the user selects a so-called "rapid freezing operation", the activation time interval of the compressor is merely lengthened without changing the rotation speed of the compressor, that is, the refrigerating capacity. This problem is caused by a fact that the conventional compressor is embodied by an A.C. motor driven by a commercial A.C. power supply source.
Furthermore, the conventional control apparatus has a problem in that the increase in the temperature of a refrigerating compartment which is caused by the frequent use of the refrigerator cannot be actually prevented because the activation of the compressor is controlled according to only the temperature of the freezing compartment.